Disc drives are among the most widely used means for storing massive amount of data, and must therefore be very reliable. Recently, disc drives are increasingly found in hand-held or portable electronic devices such as audio-visual media players and recorders. Since the majority of these devices are battery-operated, there is now also a need for disc drives to operate with minimal power consumption.
A disc drive typically includes one or more discs mounted on a spindle motor, as well one or more sets of read/write heads configured for writing data to or reading data from the discs. The read/write heads may be coupled to an actuator arm assembly and moved thereby to read data from or write data to various areas or tracks of the discs.
While the read/write heads are configured to “fly” over the surface of a rotating disc when the disc drive is in operation, it is desirable to keep the read/write heads away from the disc surface when the drive is not in operation. This is to avoid inadvertent contact between these components, as they may result in damage to the disc and the corruption of data. For this and other reasons, a disc drive may at certain times “unload” the read/write heads to a ramp positioned next to the disc. In an unloaded state, at least part of the actuator arm bearing the read/write heads will be engaged by the ramp, with the read/write heads suspended away from the disc.
In an exemplary unloading operation, the read/write heads are moved in a direction opposite to a retract direction until the actuator arm is brought to rest by collision with an inner stopper. The actuator arm is then driven by a constant voltage to move in the retract direction, all the way from the inner stopper, up the ramp, and to the rest position on the ramp.
While this may be feasible for some types of disc drives, there remains a need for solutions that will be more efficient and less demanding on the limited power resources of disc drives intended for use with portable consumer electronic devices.
The present invention provides a solution to this and other problems besides offering other benefits, as described below.